PPP is designed precisely to allow fair comparisons. The article refers to it as "international dollars". It is important to note it did not refer to USD anywhe

PPP is designed precisely to allow fair comparisons. The article refers to it as "international dollars". It is important to note it did not refer to USD anywhere: it is talking about $30PPP per day, which in real currency is a wildly variable amount but which buys approximately the same things. Without understanding the distinction between PPP and USD, it is not possible to fully comprehend the article.